Nanoparticles are ubiquitous and by far the most abundant particle-like entities in natural environments on Earth and are widespread across many applications associated with human activities. There are many types of naturally occurring nanoparticles and man-made (engineered) nanoparticles. Nanoparticles occur in air, aquatic environments, rain water, drinking water, biofluids, pharmaceuticals, drug delivery and therapeutic products, and a broad range of many industrial products. Nanoparticles usually occur within polydisperse assemblages which are characterized by co-occurrence of differently sized particles.
Given the widespread usage of nanoparticles, the ability to control and accurately characterize their properties may be useful to many applications. Conventional methods for measuring nanoparticle properties may be inaccurate for polydisperse samples of mixed nanoparticle sizes, which are common in many applications. Some of these conventional approaches make measurements on an ensemble of a large number of nanoparticles within a sample. Because the light scattered from all nanoparticles is measured simultaneously, it may be difficult to resolve the nanoparticles into their constituent sizes when there is a range of particle sizes. Other approaches fail to account for the large differences in the intensity of scattered light produced by differently sized nanoparticles across the range of nanoparticle sizes. In these approaches, the low scattering signals from small nanoparticles may be undetected, or the high scattering signals from larger nanoparticles can obscure the signals from smaller nanoparticles. As a result of these deficiencies, the concentration of nanoparticles of any given size, and hence the entire size distribution, can be subject to unknown error.